(1) Field of the Invention
This invention relates to tools and more particularly to a machine wrench for round work.
(2) Description of the Prior Art
In the drilling of oil wells, and other oil field work, it is often necessary to run pipe or drill stem in and out of the well. In drilling wells, when it is necessary to remove the drill stem from the well, one or more sections of drill stem are pulled from the well and the joint "broken" or initially loosened by tongs. Thereafter, the sections are spun loose to completely disconnect the joint. The disconnected joint or joints are then moved to one side and another section or sections are lifted from the well.
Basically, the same steps are performed in reverse to place pipe or drill stem in a well.
Oil drilling industry requires extremely rugged equipment not only are the loads and the forces on the equipment very great, but also because of the urgent need to operate the equipment often times it receives rough handling in being roughly used and the equipment itself dropped or sometimes other pieces of equipment dropped upon top of it.
A traditional way of spinning the drill stem or the pipe is to wrap a chain around the pipe and then pull the chain, thereby spinning the pipe.
It will be understood that often times the drill stem or pipe is stressed to near its limit. Therefore, it is desirable not to damage the surface of the pipe inasmuch as this in itself will inherently weaken the point where toothed jaws bite deeply into the pipe. Furthermore, often the pipe is coated to prevent corrosion or damage.
Many of the prior art devices engage the pipe for spinning with toothed jaws or chains which tend to damage the surface of the pipe being spun.
Before this patent application was filed, a search was made in the United States Patent and Trademark Office which showed the following patents:
Mason U.S. Pat. No. 3,086,413 PA1 Wilson et al. U.S. Pat. No. 3,122,211 PA1 Campbell U.S. Pat. No. 3,380,323 PA1 Duke et al. U.S. Pat. No. 3,521,509
WILSON ET AL. discloses a pipe spinner for such use. The spinner spins the pipe by three rollers bearing against the pipe, one of which is hydraulically actuated against the pipe. The three rollers are driven by a chain drive from a single hydraulic rotary motor.
It appears that the other three patents are no more pertinent than the WILSON ET AL. patent.